“We are getting less steps. We are moving less throughout the day, but our amount of purposeful activity [exercise] is actually going up. And what that is resulting in is statistically significant decreases in things like resting heart rate,” McDonough told attendees of Fortune’s digital Brainstorm Health conference on Wednesday.

And not only are Americans exercising more, McDonough says, but based on data collected from its more than 30 million users, many people are also getting increased rest and more consistency in their sleep. Those are both key for maintaining strong immune systems, she added.

The billions of data points that wearables like Fitbit and Apple Watch collect can do a lot more than simply tell us how we’re spending our time during the pandemic. McDonough told Fortune‘s virtual Brainstorm Health attendees that the data could even be used to influence health care, and perhaps even help detect COVID-19 earlier.

“Based on some earlier work we did with Scripps Research Institute, they published some data in The Lancet that was looking at [Fitbit] data that was able to take heart health metrics and look at those and then be able to look at early detection of the flu,” McDonough said.

Now Fitbit is launching a clinical trial to look at heart variability and respirations rates, and how those can be early indicators of illnesses, like COVID-19, she said.

“We have a lot to learn about COVID-19, but being able to understand asymptomatic and pre-symptomatic are really important pieces. And the earlier we can catch the illness, the safer we can leave communities and business and education,” McDonough said. “What wearables do is help make what was previously invisible, visible.”